1. Field of the Invention
The present invention relates to a vacuum vapor deposition system for vapor-depositing metal such as aluminium or the like or non-metal such as ceramics or the like onto a plastic film such as, for example, a film of polyester or the like or onto a paper sheet, and a vacuum vapor deposition system for vapor-depositing metallic material or non-metallic material onto a substrate of various non-metallic materials other than plastics or various metallic materials.
2. Description of the Prior Art
Heretofore, vacuum vapor deposition onto a plastic film, a paper sheet and the like has been carried out according to a batch system, but a continuous vacuum vapor deposition system in which a base plate is continuously carried into a vacuum vapor deposition apparatus has not been put to practical use. For reference, a continuous vacuum vapor deposition system for dealing with a steel sheet in the prior art is illustrated in FIG. 9 and will be described in the following.
In FIG. 9, reference numeral 001 designates a base plate, numerals 002a, 002b, 002c, ... designate inlet side seal rolls, numerals 003a, 003b, 003c, ... designate outlet side seal rolls, numerals 004a, 004b, 004c, ... designate vacuum pumps, numeral 005 designates a vapor deposition apparatus, numerals 006a, 006b, 006c, ... designate pressure chambers, numeral 007 designates a vapor deposition chamber, numeral 008 designates deflector rolls, and numeral 009 designates a wrapping roll.
The base plate passes through the pressure chambers 006a, 006b, 006c, ... partitioned by seal rolls 002a, 002b, 002c, ... each consisting of a pair of pinch rolls, then reaches the vapor deposition chamber 007 held at a predetermined degree of vacuum, and after it has been plated by vapor deposition by means of the vapor deposition apparatus 005 within the vapor deposition chamber 007, it passes through the outlet side seal rolls 003a, 003b, 003c, ... and is delivered into the atmosphere.
The details of each seal roll are illustrated in FIGS. 10 and 11, FIG. 11 being a cross-section view taken along line XI--XI in FIG. 10 as viewed in the direction of arrows.
In FIGS. 10 and 11, reference numerals 1011 and 1012 designate a pair of pinch rolls, numeral 1014 designates seal bars, numeral 1016 designates a casing, numeral 1017 designates an upstream side pressure chamber, numeral 1018 designates a downstream side pressure chamber, numerals 1019a, 1019b and 1019c designate leak gap clearances, more particularly reference numeral 1019a designates a gap clearance between the pinch roll 1011 and the seal bar 1014, numeral 1019b designates a gap clearance between the axial end of the pinch roll 1011 and the casing 1016, and numeral 1019c designates a gap clearance at the portion where the base plate 001 is not present between the pinch rolls 1011 and 1012.
The upstream side pressure chamber 1017 and the downstream side pressure chamber 1018 are partitioned by the pinch rolls 1011 and 1012 and the seal bar 1014, and gas flows from the upstream side to the downstream side through the above-described small leak gap clearances 1019a, 1019b and 1019c.
In addition, a process of forming a thin film by vacuum vapor deposition according to the above-mentioned batch system that is available for vapor-depositing metal or non-metal onto a base plate such as a paper sheet, a plastic film, etc. in the prior art, is such process that a preliminarily coiled base plate is charged within a vacuum envelope, and after the vacuum envelope has been sufficiently evacuated, vapor deposition is effected onto the base plate while it is running. One example of such batch systems in the prior art is illustrated in FIG. 12.
In FIG. 12, a coiled base plate 201 is charged within a vapor deposition chamber 202 as connected to a take-up reel 205 via a deflector roll 203 and a cooling roll 204. After the space within the vapor deposition chamber 202 has reached a predetermined degree of vacuum as evacuated by a vacuum pump unit 2012, the base plate 201 is made to run as pulled by the take-up reel 205, and while it is cooled on the cooling roll 204 so as to suppress temperature rise caused by heating upon vapor deposition, the base plate 201 is vapor-deposited by a vapor deposition apparatus 207. The vapor deposition apparatuses 207 are disposed in multiple at a predetermined interval in the widthwise direction of a vapor deposition material 208 and the base plate 201, each vapor deposition apparatus 207 is constructed of a container 209 for accommodating a vapor deposition material and a heating device 210 for heating the container 209, and it evaporates the vapor deposition material 208 towards the running base plate 201. Since the vapor deposition material 208 evaporated at this time would sputter not only to the just above but also in the oblique directions as spreading, edge masks 2011 are disposed at the positions overlapping the respective edge portions of the base plate 201 as spaced therefrom so that the sputtered material may not deposit onto the portion of the cooling roll 204 itself exceeding the width of the base plate 201. As described above, the vapor deposition work is a batch type of work, in which the number of the vapor deposition material containers 209 and the positions of the edge masks 2011 are preliminarily set by hand in accordance with the width of the base plate for each coil, and then evacuation, heating, running, vapor deposition and exposure to the atmosphere are effected repeatedly.
In the vacuum vapor deposition apparatus in the prior art as illustrated in FIG. 9, it is necessary for allowing the vacuum pumps 004a, 004b, 004c, ... provided to have a small capacity, that the area of the clearance 1019a-1019c is small so that the flow rate of the gas from the upstream side to the downstream side is small.
However, the gap between the rotating pinch roll 1011 or 1012 and the stationary seal bar 1014 or the stationary casing 1016 cannot be made smaller than a certain value in order to prevent contact therebetween, and so reduction of the clearance was limited.
In addition, when gas flows through the gaps, fluttering of the base plate 001 would occur, and there was a distinct possibility of the generation of creases in the base plate 001 or the cutting off of the base plate 001.
In addition, essential reasons for the fact that vapor deposition of the base plate 201 has been effected according to the batch system while continuous vapor deposition has not been practiced with the vapor deposition system shown in FIG. 12, are as follows. Firstly, an evacuation rate for generating a pressure gradient from the atmosphere side to the high vacuum side is enormous, and so, an evacuation pump system capable of operating at such a rate is very large. Therefore, as described above, the system in which a running base plate was pinched by seal rolls so that clearance between the adjacent pressure chambers was reduced, was employed. However, in the case of a thin base plate such as a paper sheet or a plastic film, scratches would be generated on the base plate by pinching, and because this is a fatal defect in view of quality of products, such a system was difficult to be put to practical use. Secondly, when the running base plate passed through the pressure chamber, the base plate would be fluttered by air flowing through the gap between the pressure chambers, thereby causing scratches and breaking.
A third problem resides in that since the vapor deposition material evaporates from the vapor deposition material container and sputters broadly, not only is it deposited onto the base plate, but it is also trapped on the mask. In the case of the batch system, a period of one batch is short, hence the accumulated amount of the sputtered material is little, and a work of removing the accumulated material could be carried out for every batch. But in the case of the continuous system, the vapor deposition material trapped by the mask, the cooling roll and the like would successively increase the accumulated thickness, so that the gap clearance between the cooling roll and the mask would be blocked, and this becomes a cause for damaging the base plate passing through the gap clearance. Furthermore, in the case of the continuous system, it is necessary to be adapted for change of width of the running base plate, hence if the vapor deposition material is trapped on the cooling roll, depending upon the width the base plate would pass over the trapped vapor deposition material, and so, vapor deposition would become difficult. This problem can be said to be a very serious problem in practical use, in view of the fact that according to the batch system in the prior art the yield of the vapor deposition material is 50% or less.
A fourth problem in the prior art resides in that since vapor deposition material is evaporated from a plurality of vapor deposition material containers, vapor spreading upwards from one container would form a vapor deposition film as overlapped with vapor evaporated from the adjacent containers, and so, in order to attain a uniform film thickness distribution in the widthwise direction, a skilled technique for controlling the temperature of the respective vapor deposition materials is required. In other words, in order to achieve continuous vapor deposition it is necessary to be continuously adapted for different base plate widths, and monitoring of the temperature of the individual vapor deposition materials and increase or decrease of the number of heated containers have a large time constant and are very disadvantageous in practical use.
Besides the above-described principal problems, in order to realize continuous operations, it is necessary to achieve continuous feeding of a vapor deposition material from the atmosphere into the vacuum envelope as well as continuous feeding and winding of the running base plate, but in practice, any practical proposal for resolving the above-mentioned problems has not been made, and so, the continuous system has not been realized.
Moreover, the vacuum vapor deposition system of the one-batch one-coil type in the prior art as illustrated in FIG. 12 is inefficient and poor in productivity.
Furthermore, it becomes necessary to expose the vacuum chamber to the atmosphere, upon every batch in the case of the batch system shown in FIG. 12, and when the running base plate has been cut or when something unusual has been generated within the vacuum chamber in the case of the continuous system wherein the base plate is made to run continuously. Then, each time a crucible is exposed to the atmosphere at a high-temperature state of 700.degree. C. to 800.degree. C., and sometimes at 1400.degree. C., and therefore, the life of the crucible is shortened due to thermal damage. In addition, in order to prevent damage of the crucible, a work of ladling out a vapor deposition material such as aluminium or the like within the crucible and a work of taking care of the crucible are necessary.